Oil burner



Aug., @9 E46., L F. SPEARE OIL BURNER Filedqune 19, 1944 2 sheets-sheet1 Emma-wm@ JPM #f1 ATTOR N E Y S Aug, 6? NM26, l LyFQsPEARE OIL BURNERFiled June 19., 1944 A 2 Sheets-Shawl*l 2 ...m Y ...y um

' ORNE Patented Aug. 6, 1946 v OIL BURNER Leolyn F. Spearc, Westfield,Mass., assigner to Gilbert & Barker Manufacturing Company, WestSpringfield, Mass., a corporation of Massachusetts Application June 19,1944, Serial No. 540,957

2 Claims.

This invention relates to improvements in oil burners of the so-calledgun type, such as are adapted for use in residential heating and arestarted and stopped many times each day during the heating season.

A gun type burner utilizes a so-called mechanical or pressure-atomizingnozzle, located near the outlet end of a tube, through which the air forcombustion is supplied by a fan, usually driven by an electric motor.The oil is supplied by a pump, also driven by the motor. Oil is admittedunder the control of a cut-ofi' valve to the nozzle only after it hasbeen placed under a predetermined minimum pressure suiicient foratomization. This pump is positive in action. Furthermore, it usuallyhas aV capacity in excess of normal requirements for combustion andexcess oil is bypassed after a certain predetermined maximum pressurehas been reached. The fan, howevenis not positive in action.Consequently, when the burner motor is started, the pump will place theoil under atomizing pressure before the fan has established flow of airat proper pressure and velocity at the outlet end of the air tube. Poorcombustion results and the smoky llame deposits soot in the combustionchamber and passes of the boiler. On stopping of the burner motor, theair flow drops c-if rapidly and before the cut-off valve closes, therate of flow of air at the nozzle is too low for the proper combustion.

This invention has for its general object the provision of means forimproving combustion conditions during the starting and stoppingintervals of operation of a burner of the class described. A

The' invention has for one particular object to provide in a burner ofthe class described, means whereby flow of air at the desired pressureand velocity is established at the burner nozzle at an earlier time inthe starting period and sustained for a longer time in the stoppingperiod than has heretofore been possible in an ordinary gun type burner.

According to this feature of the invention, a bypass is provided fromthe outlet of the fan together with a damper to control the by-pass andthe damper is arranged to open when the air supplied to the tube attainsthe required pressure and velocity. The shutter or air valve associatedeither with the inlet or outlet of the fan is adjusted to admit to thetube all the air that is needed for combustion when the fan is revolvingat some speed less than its normal full speed, say for example,three-quarters speed. The damper is set to open at the required staticpressure.

Accordingly, when the burner motor is started, the fan produces thedesired flow of air at an earlier time in the starting period thanheretofore and, after the selected predetermined speed has beenexceeded, the damper opens and bypasses excess air, maintaining thepressure and velocity of the air supplied to the tube constant. Also,during the stopping interval of the burner the flow of air is maintainedfor a longer interval. As the fan slows down, the damper moves towardclosed position and the air flow to the combustion tube is maintained atthe proper pressure and velocity for a substantial part of the stoppinginterval. By fixing the predetermined speed, at which the damper opensand'closes, to correspond with that at which the oil cut-'olf valveopens and closes, good combustion conditions can be had during thestarting and stopping intervals. Y

As a desirable additional feature, the invention provides an oil controlvalve, such as an-electromagnetically operated valve, connected so as toopen only when the damper in the air by-pass opens and to closecoincidentally with the cutting off of current from the driving motor.This oil control valve insures that, on starting up the burner, oilcannot be admitted to the nozzle of the burner until air at properIpressure and velocity is being supplied to the burner nozzle and that,on stopping the burner, oil ow to the nozzle will be cut off before thepressure and velocity of the air supplied to the combustion tubedecreases below the desired values.

The invention will be disclosed with reference to the accompanyingdrawings in which- Figs. 1 and 2 are small-scale side elevational andtop plan views respectively of an oil burner embodying the invention; l

Fig. 3 is a fragmentary sectional plan view taken on the line 3 3 ofFig. 1 and drawn'to a larger scale;

Fig. 4 is a cross sectional view taken on the line 4 4 of Fig, 3;

Fig. 5 is a view taken similarly to Fig, 3 and showing a modication ofthe invention;

Fig. 6 is a cross sectional view taken on the line 6 6 of Fig. 5; and

Fig. 7 is a diagram showing electrical connections used with the form ofburner shown in Fig. 5.

Referring to these drawings; the invention isy shown, by way ofillustrative example,- in connection with a so-called gun-type oilburner of well known form. The combustion tube is shown at l (Figs. 1and 2), fixed to the outlet end 2 of a fan housing 3, in which isrotatably mounted a fan 4, driven by an electric motor 5. As shown, the

3 outlet 2 is square in cross section and it is connected to thecylindrical tube I by a sec-tion 2', which changes from square tocircular cross Section. The parts I, 2 and 2 provide an air-supply isshown at 8.. The outlet of the pump is connected by piping 9 to thenozzle support I0-and thus to nozzle 6. Interposed inthis;V piping is aunit II containing a cut-oi?v valve and' a by-pass valve of usual or anysuitable form. The cut-ofi valve closes the outlet to the oil hasreached a predetermined minimum to the fan and thus also driven by motor5. The suction pipe for the pump.l

the burner nozzle Iiuntil pressure and the by-pass valve subsequentlyby-Y passes oil by way of a pipe I2, to any lsuitable point,` such as vthetank or the suction sideof pump 1, whenever the oil reaches apredetermined maximum pressure.

The adjustment for varying the volume of air enteringtube I from the fanmay be elected in any suitable way and on the discharge as well as onthe intake side of the fan. In this particular case, the adjustment ionthe intake side. Fixed to one side of theifan housing is a casing i3affording a chamber I4v in communication with the inlet side of the fan.Openings I5 provide for communication of the chamber I4 with theatmosphere. A Valve or damper I6 is mounted for adjustment axially ofshaft 'I' on which it is slidable, and controls the amount of air tha-tcan enterchamber I4 by way of openings I5 to. the fan. As shown, theYhub ofthe damper is threaded on a screwy I1, having its outerI end.rotatably mounted in theend of casing i3 and itsrinner endsimilarlymounted in a .lugA I1', depending from the top of the casingI3'.` The screw is heldagainst axial movement, as indicated in Fig; 3.

The oilis ignited by spark electrodes I8, mounted, in insulators I9, ina member- 2t which also supports the member It*Y and nozzle @from tubeI1.

This invention provides fora second and venting outlet for theair-supply conduit. Conveniently, this venting outlet may connect withthe intake sidev of the fan, thereby providing a bypassbut this is notessential. is constructed toprovide a chamber 2l 'above the outlet 2 andan opening 22' by meansV of which communication between the outlet 2 andchamber 2l may be established'.v The chamber 2l is'connectedloyY a tube23Y to the inlet chamber- I4v at a location between the fan inlet andthey innermost position which damper IS is likely to assume. Controllingthe openingY 22 is a valve or damper 24 mounted on a pivot 25 locatedofi centerl as shown.. A removable cover 26 provides-access to thechamber 23. Fixed to the damper is an arm 21 on which is adjustablymounted aweight 28, tending-to hold the damper-- closed. Ailug 29 on oneend of the damper cooperates with the base wall of" chamberl 2 Il as astop toprevent counter-v clockwise movement (as viewed irl-Fig. 4s)beyond the closedv position shown.

The damper-or air inlet valve I6 is adjusted to admit all the air thatis required, for combustion while the ian is revolving at some.predetermined speed less than itsv normal and full speed, such forexample as three-quarters speed. The-weight 28 is adjusted so that thedamper 24rwill openl after the desired predeterminedY static pressure--of the air in the combustion tube has beenvat- The ian housing` ,-1

- up the necessary oil pressure,

flow decreases at all'. The

tained. When the fan is revolving at full speed it would supply air at agreater rate of flow than is needed except for the by-pass valve ordamper 24 which opens as much as is required to maintain the pressureand velocity of the air in tube I substantially constant at the desiredvalues. In .this-way, it is insured vthat air,` will be flowing throughthe tube I past the burner nozzle at the desired rate after the motorreaches the selected predetermined speed and thereafter during theremainder of the starting interval, as well as during the normal runninginterval and during the initialA part of the stopping interval.According to former practice, maximum air flow was not reached untilthe'fan attained full speed. With the present invention maximum air owis secured when` the fan reaches '75% of its normal speed and, ofcourse, an even lower speed may be selected, if desired. The object isto get full air flow at or about the time that the oil cut-offvalveopens and allows nozzle 6 to emit a spray of atomized oil. Theparticular speed at which damper 24 opens is a matter of choice, and maybe-variedas is necessary or desired.

As an added feature of reiinement` to. secure and insure closercoordination between proper oil flow and airflow, a valve S isinterposed in the oil piping 9 between the cut-oir valve and nozzle 6and is suitably arranged to prevent flow of oil to nozzle B until theproper flow of air has been established duringthe starting interval ofoperation of the burner and before the air flow drops below the desiredrate during the stopping interval of operation of the burner. The valvemay for example, be al solenoid valveopening only when the solenoid isenergized and remaining open for so longas `the solenoid remainsenergized. The damper 24 may serve, as indicated, to move a mercury tubeswitch 3I from openl to closed position as the damperopens and fromclosedto open position as the damper closes. The electric circuits areindicated in Fig. 7. The burner vmotor 5 and the ignition means 40 areconnected in parallel in a circuit including the wires'35 andv 3S. Theroom thermostat switch 32y is interposed between the wires Skand 3B'.The wires 34 and 35 are adaptedv for connection to a suitable source ofelectricity. The solenoidr valve S0 is in a seriesl circuit whichcomprises the Wires 31, 38 and 39 and is shunted across the wires 3:5and 36. The room thermostat switch starts and stops theburner motor inthe usual way. Energization of the burner motor will start thepump andfan-but, irrespective of when the pump builds there will. be no.remission of oil fromnozzle S unless and until flow or" air at the properpressure and velocity,v and thus at the proper rate, has beenestablished in tube I. Then, and then only, will damper 2.4' open. Theclosing of switch 3l and the opening of oilvalve Sil-is conditioned onthe opening of damper 24;- When the burner motor is deenergized, the oilvalve 30 will immediately close and cut 01T- therflow of oil to thenozzle before the air continuance of air flow afterroilY flow is-anadvantage becauseofy the scavengingeffect.

The control of the oil howy by means cuor'- dinated withA the byi-passValve 24. may beraccom plish'ed': in any other suiiableway.` and neednotnecessarily. be conned tothe use of a solenoid valve locatedn as shown.The important. thingv is to prevent the oil from issuing. from the.nozzle except-at vsuchtimestas air at. properpressure Y andvelocityisavailableat the outlet of tube I1.

It will thus be seen that the invention provides for the improvement ofcombustion conditions during the starting and stopping intervals ofoperation of a burner of the type described. With the use of the oilvalve, the desired results may be insured so that combustion cannotoccur except when there is both a proper ow of air and a proper ow ofoil. The burner may be adjusted for a higher CO2 reading, and thus formaterially increased efficiency, when the improvements of this inventionare used.

It should also be noted that the coordinated control of oil and airoffers insurance against operation of the burner under any conditionswhich cause less than the normal supply of air. If the air openings I5become stuled up with dirt, lint or anything else, or if for any otherreason, air at the desired rate cannot be supplied to the combustiontube, then the oil valve 3l) will remain closed and prevent combustion.

I claim:

1. In an oil burner, a casing providing a fan housing having intake anddischarge openings and a conduit communicating at one end with saiddischarge opening and having an outlet at its other end, a fan in saidhousing between said openings, an oil-atomizing nozzle in said conduit,an oil pump connected to supply oil to said nozzle, a motor for drivingthe fan and pump, said conduit having a second and venting outletlocated between the fan and nozzle, a valve for the second outlet foropening and closing the same, and a valve for one of said openingsadjustable to vary inow of air to said conduit and adjusted to admit allthe air required for combustion when the fan is revolving at apredetermined speed less than its normal speed and the rst-named valveis closed, said first-named valve closing and opening automaticallyaccordingly as the fan revolves below or above said predetermined speedrespectively.

2. In an oil burner, a casing providing a fan housing having intake anddischarge openings and a conduit communicating at one end with saiddischarge opening and having an outlet at its other end, a fan in saidhousing between said openings, an oil-atomizing nozzle in said conduit,an oil pump connected to supply oil to said nozzle, a motor for drivingthe fan and pump, said conduit having a second and venting outletlocated between the fan and nozzle, a valve for the second outlet foropening and closing the same, a valve for one of said openingsadjustable to vary iniiow of air to said conduit and adjusted to admitall the air required for combustion when the fan is revolving at apredetermined speed less than its normal speed and the first-named valveis closed, and adjustable means for holding the rst-named valve closeduntil the air reaches a predetermined pressure.

LEOLYN F. SPEARE.

